osdep: initialize glib threads in all QEMU tools

glib versions prior to 2.31.0 require an explicit g_thread_init() call
to enable multi-threading.

Failure to initialize threading causes glib to take single-threaded code
paths without synchronization.  For example, the g_slice allocator will
crash due to race conditions.

Fix this for all QEMU tool programs (qemu-nbd, qemu-io, qemu-img) by
moving the g_thread_init() call from vl.c:main() into a new
osdep.c:thread_init() constructor function.

thread_init() has __attribute__((constructor)) and is automatically
invoked by the runtime during startup.

We can now drop the "simple" trace backend's g_thread_init() call since
thread_init() already called it.

Note that we must keep coroutine-gthread.c's g_thread_init() call which
is located in a constructor function.  There is no guarantee for
constructor function ordering so thread_init() may only be called later.

Reported-by: Mario de Chenno <mario.dechenno@unina2.it>
Signed-off-by: Stefan Hajnoczi <stefanha@redhat.com>

1 files changed, 0 insertions, 8 deletions

diff --git a/vl.c b/vl.c
index acd97a8..2355227 100644
--- a/vl.c
+++ b/vl.c
@@ -2970,14 +2970,6 @@ int main(int argc, char **argv, char **envp)
     qemu_init_exec_dir(argv[0]);
 
     g_mem_set_vtable(&mem_trace);
-    if (!g_thread_supported()) {
-#if !GLIB_CHECK_VERSION(2, 31, 0)
-        g_thread_init(NULL);
-#else
-        fprintf(stderr, "glib threading failed to initialize.\n");
-        exit(1);
-#endif
-    }
 
     module_call_init(MODULE_INIT_QOM);